Surface enhanced electrochemiluminescence of the Ru(bpy)32+/tripropylamine system by Au@SiO2 nanoparticles for highly sensitive and selective detection of dopamine

Abstract

Surface enhanced electrochemiluminescence (SEECL) emission of the Ru(bpy)32+ (bpy = 2,2′-bipyridyl)/tripropylamine (TPA) system by Au@SiO2 core/shell nanoparticles (NPs) was achieved owing to the electromagnetic field enhancement induced by localized surface plasmon resonance (LSPR) of internal Au cores. The Ru(bpy)32+/TPA system in electrolyte solution showed a maximum ECL enhancement when a glassy carbon electrode (GCE) was modified with Au@SiO2 NPs (Au@SiO2/GCE; Au core, ca. 68 nm; silica shell, 12 nm). The ECL emission of the system in the case of Au@SiO2/GCE was 29 fold stronger than the ECL emission in the case of bare GCE, ca. 39 fold stronger than the ECL emission in the case of hollow silica NP-modified GCE, and 100 fold stronger than the ECL emission in the case of AuNP-modified GCE. To the best of our knowledge, the respective folds of ECL enhancement in the Ru(bpy)32+/TPA system by the LSPR-induced electromagnetic field of AuNPs are the largest reported to date. The ECL emission of TPA•+ radical cations was detected for the first time taking the advantage of the electromagnetic field enhancement. A SEECL platform based on the Au@SiO2/GCE in the Ru(bpy)32+/TPA system was constructed for the detection of dopamine (DA). This is the first example that the AuNP-enhanced ECL emission was quenched by DA for the selective detection of DA, and a wide linear range of 0.01–600 μM directly relevant to DA concentration was obtained with a low detection limit of 0.004 μM and high sensitivity and accuracy. The mechanism that the ECL emission of the Ru(bpy)32+/TPA system was quenched by DA for the detection of DA was clearly elaborated. The level of DA in human serum was determined using the SEECL platform.